18650 trolling battery solar charger

[dbldrew]

Ok so have some questions on charging a battery pack built with 18650 cell. So basically the background of what im doing is every other year or so we go up camping up to MN up near ELY. Its a big camping/fishing trip. It is all canoe fishing, and a few years ago I put a small trolling motor on my canoe, which works great. But the 100ah battery im using is super heavy and just doesn't last. The place where we stay does not have any electricity. So in the past I have just pulled out the battery and put jumper cables on it from my running truck to charge it back up.

Now I want to change my set up for a couple of reasons. Some times we have to do small portages (carrying the canoe across land from one lake to another) and that huge lead acid battery is super heavy. And I also want another option for charging. So I'm in the process of making some battery packs out of 18650 cells. And I was going to charge them using 200W solar

The charge controller is a Renogy Wanderer 10 Amp 12V/24V PWM Negative Ground Solar Charge Controller
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

the solar panels Im using is 4 -50W flexible panels

https://www.ebay.com/itm/353095224156

So I was thinking of making 2 smaller battery packs rather then having just 1 big one like i had before, so 2 that are around 50ah ea, that way one will be on the solar charging up all day while the other is being used.

My old lead acid was a walmart "deep cycle" battery that was rated at 105ah and I could get around 2 ish days of use out of it before it would drop down to around 12.00V which is ballpark around 50% drained and everything I have heard is to make them last dont discharge below 50%

So one of my questions is in the AH rating of the different batteries. Is that 105ah battery rated for safe usable power? like the 105ah is based on only a 50% discharge rate? or is the 105ah based on completely draining the battery?

So I know that Lithium Ion has a much high % of usable power so im trying to get a ballpark number of cells to use to get comparable same "2 days of use"

Which brings me to my next question 12.6v or 16.8v? I have seen a lot of people building trolling motors using 4 in series rather then 3 to get 16.8v. a 18650 fully charged is 4.2v while drained is around 3v. So if i build it in 3 in series that gives me a 12.6v battery which sounds perfect. But drained im looking at 9v so not sure at what point the lower voltage will not work with the trolling motor. Which is why i have heard of people using 4 in series to get 16.8v down to a 12v drained battery.

So I was leaning towards the 4 in series to get the 16.8 volts, but what about charging that high with my solar set up?

So I guess I have rambled long enough, tell me what your thoughts are and thanks in advance for any help.

[chrisski]

For the PWM charge controller I have, the only voltages it can charge is 12 Volts, or 24 volts, so there's not a 16 volt option. So if you do this system, depending on what your charge controller manual says, 16 volts may not be an option.

So you mentioned three or four of these in series. Is that your entire battery pack or will you have a bunch of these in Parallel? I think what you really need is how many watt hours your trolling motor will use. I've got no idea what your trolling motor is. but when I look up some, they can draw 50 amps at 12 volts, or 600 watts. If you ran that for an hour a day, you may need to charge the batteries for the entire solar day. Your small trolling motor may not be quite that much, so you may get more,.

Also, are you going to be able to charge this in the best sun times of the day?

I'm a total newby to this, but what I've found is solar for camping is fine unless you want to run something that has some mmph behind it. When my 600 watt solar panels on my RV is complete, I will be pushing the limits of my system to run an electric single cup coffee maker. My original goal which is basically to run around 10000 watt hours a day was way too unrealistic.

As a final thought, is your charger lithium compatible?

[PNjunction]

dbldrew - don't take this personally.

PLEASE don't take any DIY li-ion trash builds into the wilderness, since by asking these questions it shows you do not know what you are doing.

You didn't specify WHAT specific chemistry your 18650's are, but I'll bet you don't know the difference between LiFeP04 (safest) and other types.

Instead of DIY, look into something like a 50ah Battle-Born LiFeP04 battery. Or whatever capacity your homework on you load needs dictates.

I'm *begging* you not to take any diy trash stuff into the wilderness, not only for your camp's safe, but for the sake of others in the wilderness and beyond.